Insulated conductor



vJune 23, 1936. s j osc 2,045,103

INSULATED CONDUCTOR Filed May 26, 1934 INVENTOR JAMUEL JEoJ'c/v'.

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ATTORNEYS Patented June 23, 1936 PATENT OFFICE 4 2,045,103 INSULATEDCONDUCTOR Samuel J. Rosch, Yonkers, N. Y., assignor to Anaconda Wire &Cable Company, New York,- N. Y., a corporation of Delaware ApplicationMay 26, 1934, Serial No. 727,642

5 Claims.

This invention relates to electric conductors and more particularly toa; conductor having insulation in the form of asbestos carried by arelatively tough backing strip or tape.

The use of asbestos is not broadly new. But, so far as I am aware it hasnot been possible heretofore to apply asbestos in the form ofthintape-like wrappings because it has very little tensile strength andis, therefore, incapable of withstanding the tension which isnecessarily imposed when wrapping it about a conductor.

A feature of my invention relates to an improved insulating tape adaptedto be wrapped about a conductor or over other insulation carried by theconductor; this tape being formed of a relatively tough backing stripfaced with asbestos fibres. The backing strip can be of cellulosecomposition such as Cellophane. Or, it may be of a tough paper such asglassine or the like.

In some cases, the asbestos will'be calendered' and adhesively unitedwith the tough backing strip. It is also contemplatedto provide a stripof coarsely interwoven strands having asbestos fibres interspersedthroughout the net-like structure, this interspersed body of asbestosbeing se-' cured to a tough backing strip or tape of Cellophane, paper,or in some cases, to a strip or tape of cambric or other textilematerial.

Various embodiments of the invention are i1- lustrated in theaccompanying drawing, in which-Fig. 1 is a side elevation of a conductorhaving insulation incorporated therein embodying the invention; Fig. 2is a cross section of the conductor of Fig. 1; Fig. 3 is a perspectiveviewof a length of insulating tape embodying the invention, one endthereof being peeled away from another portion; Fig. 4 is an enlargedcross section of the tape shown in Fig. 3; Fig. 5 is is a view similarto Fig. 3 showing a modification wherein the asbestos fibre isinterspersed through a coarsely woven textile fabric; Fig. 6 is amodification of the improved tape applied over-a body of insulation;Fig. 7 is a cross section of Fig. 6; Fig. 8 is a modificationillustrating the improved tape applied directly to the conductor andhaving insulation enveloping the tape; Fig. 9 is a cross section of Fig.8; Fig. 10 is a detail view illustrating a modification, wherein a bodyof asbestos fibre is interposed between the backing strip and a textilenet-like strip, the-three being held together by one or more lines ofstitching.

In Fig. 1, l0 represents a suitable conductor which may be regarded aseither a solid member or a multiple strand member. This is wrapped witha plurality of layers of tapes l2. Each tape and over this there willbea plurality of layers will preferably have an outer protective jacketincludes a relatively tough backing strip I 4 of Cellophane, glassine,paper, cambric,-or the like to which is secured a relatively fiat layerof asbestos fibres such as indicated at It. Fig. 3 illustrates a shortlength of the improved tape be- 5 fore incorporation in the cableinsulation, the backing strip being peeled free from the asbestos fibresby way of illustration.

In the modification illustrated in Fig. 5, the backing strip l4 may beregarded as substantially 10 the same as that above described. Theasbestos facing in this form, however, constitutes a fibrous bodyinterspersed through the coarsely woven net-like textile fabric l8. Thislattice-like textile body serves'as a base or reinforcement and the 5fibres may be matted therein by calendering and the thus reinforced bodyof asbestos adhesively secured to the backing strip M of Cellophane orthe like. In some cases, the adhesiveunion between the asbestos body andthe tough backing strip may be secured by feeding a tissue-like strip ofgutta-percha between the backing strip and the asbestos body and thensubjecting the laminated body to heat and pressure. The gutta perchabeing athermoplastic adhesive material will then 25 unite the parts. i

Instead of adhesively uniting the asbestos to the backing strip, I mayprovide a laminated strip, such for example as shown in Fig. 10, inwhich20 represents a relatively tough backing strip of 30 Cellophane, paper,cloth or the like. Underneath this, there is a body of asbestos fibreindicated at 22 and under the fibre there is a coarsely woven strip oftextile material such as cotton nettingand the three component partsthus associated are secured by one or more lines of stitching, asindicated at 24.

The various types of backed asbestos tape described can be incorporatedin conductor or cable insulation in various manners other than thatindicated in Fig. 1. For example, as shown in Fig. 6, the conductor I0is enclosed in a body of conventional insulation such as rubber, or onemore layer of paper, indicated generally at 26,

of my improved asbestos insulation backed with a tough supportingmember. In the modification of Fig. 8, the wrappings l2" of asbestosstrip are applied directly over the conductor l0 and are in turnenveloped in a body of insulation indicated at 28, which may be regardedas a body of rubber, layers of paper, cambric or other conventionaltypes of insulation known to those skilled in the art. In each case, theconductor or cover, indicated at 3b. This may be in the form of ametallic sheath or may consist merely of a woven jacket ofinterconnected strands of cotton and twisted paper. Or, otherconventional braids and the like may be used. 77

The reinforced asbestos tape herein disclosed may be impregnated withvarious types of insulating compounds or waxes prior to the applicationon the conductor. Or such insulating compounds may be applied in betweenthe layers of asbestos tape during the taping operation. Asbestos itselfpossesses only a moderate dielectric value. But, when backed by a sheetof cellulose or the like, it is endowed with a materially greaterdielectric value.

In the event that during operation of the conductor any surface arcingshould occur as a result of a short circuit or due to a defect in theinsulating structure, even though the cellulose or other reinforcingbacking incorporated may be partly or wholly consumed for an appreciabledistance it will be appreciated that the asbestos insulation beingnon-inflammable will remain and serve as a heat resisting and electricalspacing medium between the conductor and any other conducting substancewithin the insulation body which might have a tendency to are over ifthe insulation were destroyed.

While I have described quite specifically certain embodiments of theinvention herein illustrated it is not to be construed that I am limitedthereto since various modifications and substitutions of equivalents maybe made by those skilled in the art without departure from the inventionas defined in the appended claims.

Vifhat I claim is:--

1. An electric conductor having an envelope of insulation including awrapping of tape and a body of asbestos interspersed throughout atextile network secured to said tape.

2. An electric conductor having an envelope of insulation including aWrapping of a composite tape comprising a tough backing strip, anet-like fabric facing and an intermediate filling of loosely mattedfibres.

3. An electric conductor having an envelope of insulation including awrapping of a composite tape comprising a tough backing strip, anet-like fabric facing and an intermediate filling of loosely mattedfibres, said backing strip and said facing being joined by stitchingpassing through said filling.

4. A composite insulating tape comprising a layer of asbestos interposedbetween a tough backing strip and a woven textile fabric stitched to thebacking strip.

5. An insulating tape comprising a relatively tough backing strip havingsecured thereto a relatively coarse textile netting with asbestos fibresinterspersed throughout the meshes thereof.

SAMUEL J. ROSCH.

